A Solid-state Potassium Ion Sensor From Acrylic Membrane Deposited on ISFET Device
A potentiometric K+ ion sensor made from chemically modified field effect transistor (KCHEMFET) by depositing a K+ ion-selective membrane on ion-selective field effect transistor (ISFET) has been successfully developed. The oxide materials of ISFET gate were silicon nitride (Si3N4) and silicon dioxide (SiO2). The K+ ion-selective membrane was a polymeric material from plasticiser-free poly(n-butyl acrylate) (nBA), which contained valinomycin acting as an ionophore and a lipophilic additive improving the membrane resistance. The K-CHEMFET characterization included a study on the effect of buffer solution, selectivity, effect of light and temperature, hysteresis, response time and sensor drift. The solid-state K+ ion sensor demonstrated sensitivity of 57.8±0.9 mV/decade with dynamic linear range from 0.01 to 100 mM (R2=0.9949) and detection limit of 0.003 mM of K+ ion. Besides, the repeatability and reproducibility of K-CHEMFET were 1.55 RSD % (Relative Standard Deviation) and 4.28 RSD % respectively.